<!DOCTYPE html>
<html>
<head>
    <title>表单提交示例</title>
</head>
<body>
    <h1>用户登录</h1>
    
    <!-- 表单提交到当前URL（/），方法为POST -->
    <form method="POST" action="/">
        <label for="username">用户名：</label>
        <input type="text" id="username" name="username" required>
        <br><br>
        
        <label for="password">密码：</label>
        <input type="password" id="password" name="password" required>
        <br><br>
        
        <button type="submit">提交</button>
    </form>
</body>
</html>